几种卤代酚在紫外辐照下的光降解研究

摘要

卤代酚是一类具有高毒性和持久性的有机污染物,广泛的存在于环境中而威胁到人类和野生动物的生存健康.目前现有的技术将卤代酚进行彻底和有效的去除,这是水处理中的一个挑战.本研究选取了11中卤代酚,包括7中氯酚,3种溴酚和1种碘酚,采用手段研究它们在紫外辐照下的光解转化过程.在常规条件下,当紫外计量达到9.8 ×103 J·m-2时,所有选取的卤代酚都有较高的去除率.从卤原子取代的种类、位置和程度三方面,对11中卤代酚的光降解过程进行了类比,分析其光解特性.考察了pH的影响因素,发现电离态的卤代酚有更好的光解效果.进一步的动力学研究表明,卤代酚在紫外辐照下的光解过程满足一级动力学模型.最后,对卤代酚光解过程中产生的卤离子进行的检测分析发现,在紫外辐照下,卤代酚的降解能够释放大量卤离子,实现脱卤.本研究揭示了紫外实际应用过程中卤代酚的光降解是很重要的一个转化过程,同时也为卤代酚的高效降解和脱毒提供理论参考和技术依据.%Halophenols are a category of toxic and persistent pollutants,and widely occurs in environment,threating the health of human and wildlife.The efficient and total destruction of halophenols is still a big challenge for the current technologies.The study selected eleven halophenols,seven chlorophenols,three bromophenols,and one iodophenol,to investigate their phototransformation under UV irradiation.Under ambient conditions,all studied halophenols underwent high removal ratio at UV dose of 9.8× 103 J · m-2.The photodegradation rates were compared and further discussed among chlorophenols,bromophenols,and iodophenols,concerning the kind,number,and position of the substituted halogen atoms,and tentative interpretation was proposed and some deduction was also reached.Then dependence of photodegradation on pH was carried out to compare different photoactivity of dissociated and undissociated form of halophenols.Further kinetic study was performed to explore the detailed degradation process of photodegradation of halophenols.Finally,release of halides ions was determined to explore the dehalogenation during photodegradation of halophenols under UV irradiation.The study shows the significant role of phototransformation of halophenols during practical UV application,and also provide some guidance for efficient degradation and detoxification of halophenols.